The New South Wales environmental regulator is investigating the deaths of thousands of fish in Parramatta River due to low oxygen levels.
According to the Environment Protection Authority, it was looking into two fish kill events. One at Haslams Creek last week, which flows into Homebush Bay and the other at Rydalmere this Sunday.
Many dead fish have been seen along the riverbanks.
According to the EPA, these events were likely to be caused by natural causes. Initial investigations suggest that Sunday’s fish kill was caused by storm runoff.
High intensity storms result is large amounts of organic matter like twigs, leaves and branches being washed into rivers and streams.
A spokesperson for the EPA stated that this, along with high water temperatures, likely caused a drop in oxygen.
Officials collected water samples, and water monitoring was to continue.
A spokesperson stated that it was distressing that so many fish had been killed and that a variety of species had been affected.
Authorities have warned that flood waters north of Menindee Lakes could cause more fish deaths. They also experienced massive fish kills in 2019.
Stuart Khan, the director of University of New South Wales’s graduate school of engineering, stated there was widespread concern over the Darling River’s deoxygenated waters and that nothing could be done to prevent floodwaters from reaching Menindee Lakes.
He said that the weather would play an important role as heat and high water temperatures are more likely than cold to cause fish death.
DPI [the NSW Department of Primary Industries]He stated that the company is already preparing people.
Its overland flow across floodplains, particularly floodplains which might not have flooded for a while.
They create all sorts of biomass, sticks, and leaves.
Khan stated that stormwater management could be improved in areas like the Parramatta River.
He stated that if cities were designed with more pervious surfaces, such as soils, grasses, or permeable pavements, it could slow down the pace of such events. This is because water would first infiltrate soils before flowing into waterways.
He said that it is a particular consequence of our urban design in a city.
The problem is water influxes, which can be caused by concrete construction.